Micro wave valves



y 9, 1961 c. H. LUHRS 2,983,883

MICRO WAVE VALVES Filed Jan. 15. 1953 INVENTOR CHARLES H. LUHRS RNEYS I Patented May 9, 1961 Fice MICRO WAVE VALVES Charles H. Luhrs, Teaneck, N .J., assignor to General Precision, Inc., a corporation of Delaware Filed Jan. 15, 1953, Ser. No. 331,416

4 Claims. (Cl. 333-24) this application has special advantages over said switch because the impedance matchof the elements comprising the valve remains constantat all times, irrespective of the strength of the current .flowing through the apparatus, whereas under the same conditions the impedance match between the switch and adjoining sections of wave guide varies.

An object of the invention is to provide improved apparatus for controlling the flow of micro waves.

Another object of the invention isto provide sucha device in which the impedance match remainsconstant at all times.

A further object of the invention is to provide such a device in which there will be no standing wave.

Another object of the invention is to provide such a device through which current maybe passed freelyin one direction while eliminating substantially all. current .flowing in the opposite direction.

Other objects of the invention will be in part obvious or in part pointed. out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the-several steps and'relation and 'order of each of said steps to one or more-of the others thereof,

all as will be pointed out in the following'description, and a the scope of the application of which willbe indicated in t the following claims.

The invention will best be understood if the following description is read-in connection with the drawings, in which,

Figure l'is a plan view ofanembodiment of the invention interconnected between .a source of energy and x a lengthof rectangular wave guide;

Figure 2'isalongitudinalsection, partly in cross-sec tion, of the intermediate or central portion 12 of the apparatus shown in Figure 1;

Figure ?3 is. aview in perspective of a preferred delta section insert;

Figure 4 is a detailed view showing in perspective a preferred formof one of the delta-sections'employed in the apparatusand shown in Figurel as'=1tl and 14;

FigureS is a partly schematic view showing coil 26 connected in circuit with a..D.C. bias current and an .A.C. modulating current; and

.Figure 6 -is a sideelevational view partlyuin section of a modified embodiment of the invention.

Theassembly or valve WhiChiS the subject of this application comprises a first idelta-'90,section.lllcoupled to the section 12 which in turn is coupled to a second delta section 14. Said delta sections 10 and 14 are each disposed at a 45 angle to the wave guide generator 16 and rectangular wave guide 18 to which their outer ends are respectively connected, but in opposite directions so that their principal planes are at a 90 angle one to the other.

The section 12 is characterized by the faculty of selecting for transmission only circularlypolarized wave energy having a particular direction of rotation. Two modifications of section 12 are disclosed herein for accomplishing this result.

In the modification shown in Figure 2. a section of round wave guide 20 is provided having therein abody 22 of dielectric material which is highly dichroistic. I have found that the type of ferrite which is commercially available under the trade names FerramicB, and F6-23, having the general formula is unique in its dichroistic quality and I have obtained very good results using a body of such ferrite disposed along the longitudinal axis of a section of round wave guide 20 and extending the full length of saidsection. I have obtained goodresults using a length of round waveguide 2 /2 in. long and having a diameter of with a rod of ferrite therein substantially 2 /2 in. long and having a diameter of .221 in. v

The body or rod 22 may be supported mechanically but I prefer to support it by filling the space around it within said length of wave guide 20 with substantially lossless material24 such for exampleas polystyrene, or a material comprising polytetrafluorethylene and available on the market under the trade name Teflon.

In conjunction with said body or rod of'Ferramic B means areprovided for creating a magnetic field parallel to the axis of said round wave guide section 20. This means may take the form of a permanent magnet positioned in close proximity to the round wave guide section 20, but I prefer to use a conductor coil or winding 26 extending around said section 20 and having the terminals tt across which a voltage is impressed to energize the coil and create a magnetic field. When the magnetic field is created the dichroistic strength of a body 22 of Ferramic B or F6-23 or equivalent is such that only one component of circularly polarized micro wave energy will be transmitted through said round wave guide section 20, the component of energy which is rotating in the opposite direction being dissipated or absorbed within said round wave guide section. The completeness of the selectivity thus provided varies with the current flowing through said coil, and thus by increasing or decreasing the said current within maximum and minimum limits, say, for example 0 to 360 ampere turns, the strength of the micro wave energy passed by the apparatus or valve disclosed herein maybe varied between wide limits.

There will be substantially no standing wave within the device disclosed herein since, any reflected energy will be negative i.e. opposite to'the direction of flow through the coil 26, and because of the dichroistic effect of said rod 22, substantially all reflected energy will be absorbed by the ferrite.

It will be evident that the valve structure described above functions to pass micro wave energy only in one desired direction and also to control the strength of the energy which is passed in the selected direction. -By reversing the direction of flow of current the direction of flow of micro wave energy through said valve may be reversed and the device Will function with the same selectivity as before and operate to reject-any reflected energy.

I prefer to use delta sections of the kind disclosed in my co-pending application Serial No. 266,185. As shown and described in said co-pending application the delta section made in accordance with my invention comprises a length of round or substantially round wave guide, illustrated by the numerals 10 and 14 in Figure 1, having therein an insert characterized by its shape and made of lossless material 28, such for example as polystyrene, or a material comprising polytetrafluorethylene and available on the market under the trade name Teflon. The insert 28 is characterized by its substantially cylindrical form, its periphery being partly curved, as at 30, and including at least one plane face 38. As illustrated herein, in Figure 3, the insert 28 has two oppositely disposed plane surfaces 32, and butt ends 34, which are parallel, and are at right angles to the length of the insert. The insert may be described as a plane truncated right cylinder.

My preferred form of delta section has the advantage that it has a predictable differential phase shift per unit length thus making it easy to manufacture. I have found that it gives 31.4 phase shift between the two wave components per inch of length over all portions of its length. A good impedance match exists between it and the rectangular wave guide and no tapers or other matching means are required. This is very important from the point of view of ease in manufacture and accurate reproduction. It is possible to make up a long length of wave guide with a dielectric insert 28 as described herein, and simply cut it to length according to the phase shift desired. Thus a delta section capable of providing a diiferential wave component phase shift of 90 or 135 or 180 or any other desired number of degrees, may be readily provided and is easy to connect to a rectangular wave guide section as shown in Figure 1.

I have obtained good results with a delta 90 section having a length of 2.860 inches for both wave guide section and dielectric insert 28; outside diameter of section inch; inside diameter 0.691 inch; and a distance between opposed flat faces of insert of .576 inch. A delta 180 section would have the same dimensions except that its length would be doubled.

In Figure 5 the coil 26, which may be of either Figure 2 or 6, is shown connected in circuit with a DC. bias current source such as battery 36, and a modulating current source 38 such as the DC. source illustrated. If desired a microphone may be substituted for the AC. source indicated to impress voice modulation upon the energy flowing through coil 26.

In the embodiment of the invention shown in Figure 6 the elements are the same as those described above except for the ferrite rod and the diameter of the round wave guide of section 12. In the embodiment of section 12 illustrated in Figure 6 the selectivity of a highly dichroistic body such as Ferrarnic B, or F6-23, is provided by a different means comprising, coaction between a body 40 of material active in the Faraday-magnetooptical sense, the dichroistic effect of which is not important, and may for example be made from material which is commercially available under the trade name Ferramic A, and the diameter of the length of round wave guide 42 which in this instance is critical.

For successfully using this second embodiment of the invention illustrated in Figure 6 I employ RF frequency which is greater than the cut off frequency of the wave guide section 42 for the one circularly polarized component and which is less than the cut off frequency of wave guide 42 for the other circularly polarized component. Or, stating it another way, for a particular RF frequency I employ a round wave guide 42 the cut off frequency of which for one circularly polarized component is greater than the RF frequency and for the other circularly polarized component is less than the RF frequency.

Both embodiments of the invention described above function to admit into the round wave guide containing either rod 22 or rod 40, substantially only micro wave which is positive i.e. which is circularly polarized and rotating in the same direction as the flow of current in coil 26, and any reflected energy is substantially excluded from said section of round wave guide since it is opposite in direction of rotation to the direction of fiow of current through said coil.

It will thus be seen that there has been provided by this invention a method and apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

What I claim is:

1. A microwave device comprising a length of waveguide having end sections for propagating energy in a linearly polarized mode and a center section for propagating energy in a circularly polarized mode, a pair of polarization conversion means respectively disposed at the ends of said center section, a gyroresonator axially disposed between said pair of conversion means in said center section, and a magnetizing means disposed adjacent said center section for establishing an axial steady state magnetic field longitudinally through said gyroresonator in a selected direction and of predetermined magnitude to produce gyroresonance, one of said conversion means having a configuration to convert input energy of said linearly polarized mode to a circularly polarized mode of one sense as considered in the direction of said steady state magnetic field which is substantially unattenuated by said gyroresonator, the other of said conversion means having a configuration with respect to said one conversion means to convert energy of said circularly polarized mode back to an output linearly polarized mode and to convert reflected energy to a circularly polarized mode of opposite sense when considered in the direction of said steady state magnetic field which is attenuated by resonance absorption of said gyroresonator.

2. Apparatus for controlling the flow of microwave energy in a waveguide comprising, a source of linearly polarized microwave energy, an input delta section coupled to said source for converting said linearly polarized energy from said source to circularly polarized energy, an output delta section for reconverting said circularly polarized wave energy to linearly polarized wave energy, said delta sections being spaced apart longitudinally and interconnected by a length of round waveguide having therein a body which in a magnetic field will transmit through said length of round waveguide substantially only one component of circularly polarized microwave energy, and means for creating a magnetic field interlinked with said body parallel to the longitudinal axis of said length of round waveguide.

3. A microwave device comprising a length of waveguide having end sections for propagating energy in a given non-circularly polarized mode and a center section for propagating energy in a circularly polarized mode, a pair of polarization conversion means respectively disposed at the ends of said center section, a gyroresonator axially disposed between said pair of conversion means in said center section, and a magnetizing means disposed adjacent said center section for establishing an axial steady state magnetic field longitudinally through said gyroresonator in a selected direction and of predetermined magnitude to produce gyroresonant absorption of circularly polarized energy of a given sense, one of said conversion means having a configuration to convert input energy of said non-circularly polarized mode to a circularly polarized mode of sense opposite said given sense,

as considered in the direction of said steady state magnetic field, which is substantially unattenuated by said gyroresonator, the other of said conversion means having a configuration with respect to said one conversion means to convert energy of said circularly polarized mode back to an output non-circularly polarized mode and to convert reflected energy to a circularly polarized mode of said given sense when considered in the direction of said steady state magnetic field, which is attenuated by resonance absorption of said gyroresonator.

4. Apparatus for controlling the flow of microwave energy in a waveguide comprising, a source of linearly polarized microwave energy, a first 90 delta section for converting linearly polarized microwave energy into circularly polarized microwave energy coupled to said source, a length of round waveguide coupled at one end to said first delta section, means including a body of dielectric material which is active in the Faraday-magnetic-optical sense in said round waveguide for transmitting only microwave energy received from said first delta section having a particular direction of rotation, the diameter of said round waveguide being less than the 'cutofi frequency for one circularly polarized component of the microwave energy and greater than the cutoff frequency of the other circularly polarized component of said energy, said body acting in conjunction with the diameter of said round waveguide to admit into the length thereof substantially only the component of energy the frequency of which is less than the cutoff frequency of said round waveguide, and a second 90 delta section coupled to the other end of said round waveguide, said delta sections being disposed at a relative rotary angle of 90.

References Cited in the file of this patent UNITED STATES PATENTS 2,129,669 Bowen Sept. 13, 1938 2,443,612 Fox June 22, 1948 2,458,579 Feldman Jan. 11, 1949 2,526,383 Meier Oct. 17, 1950 2,573,713 Kannenberg Nov. 6, 1951 2,599,753 Fox June 10, 1952 2,606,248 Dicke Aug. 5, 1952 2,607,849 Purcell Aug. 19, 1952 2,644,930 Luhrs et a1. July 7, 1953 2,719,274 Luhrs Sept. 27, 1955 2,741,744 Driscoll Apr. 10, 1956 2,746,018 Sichak May 15, 1956 2,748,353 Hogan May 29, 1956 2,787,765 Fox Apr. 2, 1957 2,952,821 Fox Sept. 13, 1960 OTHER REFERENCES Hogan: The Ferromagnetic Faraday Effect at M. W. Frequencies, Bell Technical Journal, January 1952, pages 1-31.

Sakiotis et al.: Microwave-Antenna Ferrite Applications, Electronics, June 1952, pages 156, 158.

Principles and Applications of Waveguide Transmission, Southworth, Van Nostrand Company, Aug. 4, 1952,

page 327. 

